Github as any git storage works so collaborators could make a local copy of your project work with it then add changes to project on Github so you can use these changes. So the straight answer yes you need whole project export to Github, but... if you work with a game engine there files which you don't need to have on Github, because game engine can generate them when you import a project from Github. When you are using git or git manager software like ex. "Sourcetree" you need to make a file called gitignore to exclude those game engine files from sending to Github. You can find templates for these files here https://github.com/github/gitignore also you might need a git LFS to send to Github larger files if you have some in your project. I hope it helps you in googling this things.
